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Ampeg V4B -- early 1970s

Discussion in 'For Sale: Amps, Preamps, and Cabinets' started by groovaholic, Nov 23, 2012.

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  1. groovaholic

    groovaholic Supporting Member

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    Selling my (according to the EIA date codes) 1973 Ampeg V4B.

    I picked this up recently "as-is".
    I did some minor maintenance(cleaning and lubing pots, switches, and jacks) and serviceability modifications, and now it's ready to rock.

    When I first got the amp home, it was 100% original--tubes & everything! But, one of the 7027's was broken.

    So, first order of business was to get a new set of tubes into it.
    I went with 6L6GC for the power tubes due to their lower cost and negligible differences from modern 7027.
    Other tubes are recent production with the exception of the 6K11, which is an NOS tube.

    Did some minor mods to the amp:
    • Some of the knobs were missing, and I couldn't afford to go with original replacements at $35/each, so I sold the remaining knobs and put replacements on it.
    • The power cord was replaced with a grounded plug.
    • The rubber feet on the amp were dried out and crumbling; I replaced them with new ones.
    • The schematic was crumbling, so I put a sheet of contact paper over it; it is 100% legible--contrary to what the pictures might suggest.

    Then a couple less-minor modifications:
    • Installed a precision 10-turn potentiometer (in series with a resistor as a failsafe) for bias adjustments.
    • Replaced the soldered-in internal 10A fast-acting fuse with the same value, but in a fuseholder to facilitate future replacement.
    • Replaced the screen resistors with 1K 5W so that the amp could more easily accomodate EL34s, 6550s, or KT88s if you wanted to use them (pin 1 is NOT connected to anything, so it's safe to do so)

    Finally, there are a couple remaining issues with the amp.
    Parts have been ordered from FlipTops and will be installed prior to shipping:
    • The Channel 2 input doesn't short out when the cable is removed, so it will hum unless the volume is down or something is plugged into it. Channel 2 is a little brighter and more lively than channel 1, so I plug in there all the time and it hasn't bothered me. The replacement jack was $3 or so.
    • The power light flickers. Originally, it didn't light at all; so I replaced a burned-out inline resistor, but that only got me partial function. I'm thinking the resistor burned out due to problems with the neon bulb. The replacement light was $8 via FlipTops.

    When I reassembled and biased this amp, it measured precisely 540VDC on the plates--which is exactly what the schematic specifies.
    So it's running strong, steady, and well within specifications.

    Alas, my Peavey Classic 400 still really satisfies my tube craving...and I have medical bills to pay.

    So, I will run this ad for a week here. If I don't find a buyer within that week, I will have to list the amp on eBay.

    If you've been craving a vintage Ampeg bass head--let me know!
    I'd definitely prefer to get it to someone who is going to play it and love it...

    $620 + shipping(price was adjusted to account for new parts)
  2. groovaholic

    groovaholic Supporting Member

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    Here are pictures of the installed fuse holder and bias pot/grounded power cord

    Attached Files:

  3. groovaholic

    groovaholic Supporting Member

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    Here is the back of the amp

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  4. groovaholic

    groovaholic Supporting Member

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    A close-up of the front panel, showing the replacement knobs, and another pic of the back

    Attached Files:

  5. groovaholic

    groovaholic Supporting Member

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    These show the schematic and the input jack area
  6. 68Goldfish

    68Goldfish Supporting Member

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    Just a free bump for one of the greatest bass amps of all time. I've got one that's been modded for 6550's and when paired with a 2x15 cab it's unbeatable. In fact my SVT has never left the house since i got the v4b.
  7. astack

    astack Supporting Member

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  8. groovaholic

    groovaholic Supporting Member

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    PM replied!!
  9. BassSurfer

    BassSurfer Supporting Member

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    PM inbound!!
  10. groovaholic

    groovaholic Supporting Member

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    PM replied!

    Also, based on a conversation with a prospective buyer, I've gone ahead and ordered the replacement parts from FlipTops.
  11. groovaholic

    groovaholic Supporting Member

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    And sold!!!!
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